Mechanically operated thumb for artificial hands



Dec. 23, 1947. F. P. SIMPSON 2,433,301

MECHANICALLY OPERATED THUMB FOR ARTIFICIAL mums Inventor F ran cis I? Simpson Patented Dec. 23, 1947 MECHANICALLY OPERATED THUMB FOR ARTIFICIAL HANDS Francis P. Simpson, New Castle, Par

Application January13, 1947, Serial No. 721,724

11 Claims. (Cl. 3-12) The present inventionrcomprises novel and. useful improvements. in. a mechanically operated thumb forartificial hands and more specifically pertains-to an improved mounting; for an artificial thumb, and an. improved. and novel actuating means for operating, the same.

The principal, objects of this invention are to provide a novelconstruction ofa movable thumb for artificial hands; to provide an improved mechanism for operating the artificial thumb; to provide in such a. mechanism a snap. action movement; to provide an operating mechanism having a mechanical advantage. or emphasized movement for causing the opening movement of the thumb; to provide a unitary assembly tor. supporting and housing the. operating mechanism; and generally to provide a dependable, durable, simple and inexpensive operating mechanism. for an artificial limbs These, together with various, ancillary objects voi the invention which will later becomeapparent as. the following description proceeds, all realized by this invention, one embodiment. of which has been illustrated byway of example only in the accompanying drawings, wherein:

Figure 1 is a longitudinal sectional through a portion of, an artificial limb illustrating the: constructionoi, the, artificial thumb. and the operating mechanism therefor in accordance with this invention;

Figure 2 is a horizontalsectional. view taken substantially on the section line.22 of Figure 1 and illustrating the operating mechanism of the artificial thumb;

Figure 3 is a verticaltransverse sectional view taken substantially upon the section line 3-301 Figure 1 and illustrating the manner of mounting the operating mechanism of the device; and

Figure 4 is a fragmentary sectional detail view taken substantially von the section line. 4,--4 of Figure 1 and illustrating the fulcrum construction of the thumb.

Referring now'morewspecifically to theaccompanying drawings, wherein like numerals, indicate similar parts throughoutvthevarious views, attention is directed primarily to Figural wherein a portion of an artificial limb indicated generallyat ill, isdepicted and shown provided withfixed hand or finger elements l2 and a hollow wrist portion l4 within the palm of whichis pivotally mounted'a-thumb la.

'As shown best in Figures 1 and 4 the thumb member in cross section atitslpivot point is generally ellipsoidal in'shape and is providedwithua longitudinallyandrearwardly opening bore 20 adapted to detachably receive the screw-threaded end 22 of anoperating lever 24 whose rearward end is curved as shown, and terminates in eye, Portion 25..

The operating lever 24- is prevented from rotating in the bore 20 and, is locked therein by a transversely extendingiulcrumed end 32 which is. engaged in a notch or recess 30 in one side of the lever 24, this end 32 being journaled in the side Walls 34 of a, generally spherical socket or seat for'snugly receiving the thumb member l8.v In Figure 1 the. open position of the thumb is shown in full lines while its closed position together with thatof. the. operating lever 24 is shown in dotted lines.

The thumb I8: is normally biased to its, open position by a spring attached as at 38 to a suitable portion of the hollow interior of the hand member l0, while the other end of the spring 40 is attached to the eye 26 of the lever 24.

Detachably connected as by a telescopic shoulder engagement 42 and fastening means 44 to the end portion I4 is a casing 46 constructed to simulate the lower portion of a. forearm. This casing is open at its inner end where it engages the wrist portion I4 and is closed at its outer end as by a plate 48 from which extends rearwardly an axial externally threaded extension 48 adapted for detachable engagement with an artificial arm member of any suitable construction, not shown. As will be set forth hereinafter, the casing 46 constitutes a unitary assembly containing the operating mechanism for the movable thumb, which casing is detachably connected and may be readily removed for servicing or repairs, from the associated hand member 10.

As shown best in Figures 1, 2, and 3, a unitary operating mechanism assembly is removably connected to the interior wall of the casing 46, and comprises a, frame plate member 52 having supporting legs or brackets 54 at the opposite extremities thereof and suitably connected to the casing 45 as by iasteningmeans 56'. Intermediate its ends. and suitably disposed thereon, the frame plate member 52 is providedwith a transversely extending recessed channel 58 for a purpose to be later set forth.

Fulcrumedupon the outer face of the frame 52 upon oppositesides of the channel portion 58 are a pair of operating levers 60 and 62 respectively, having theiropposite extremities pivotally connected by aconnecting' link 64 as at 66. The

other free extremity of the lever 60 is pivoted as at fifito an operating rod ID having an operating knob 12, this rod extending through a suitable a pivot connecting said aperture or slot 14 preferably in the lower surface or underside of the casing 46. A third lever I6 is likewise fulcrumed upon the outer surface of the plate '52 and is pivotally connected as at 18 to an operating link 80 which, in turn, is pivoted as at 82 to the operating lever 62. The other end of the lever 16 is engaged as at 90 by a spring member 92 whose other extremity is attached to the eye 26 of the operating lever 24.

It will be noted from Figure 1 that the fulcrums 84, 86 and 88 of levers 60, B2 and 16, respectively, are so chosen that an amplified movement is imparted by the operating rod H! to the connection 90 upon the spring 92, whereby a relatively slight movement of the operating button 12 will impart a greatly augmented movement to the spring 92 to tension the same. This movement can be clearly followed by comparison of the full line positions of the operating linkage and lever 24 and their dotted lines alternative positions.

The channel portion 58 of the frame 52 is so positioned as to accommodate the pivotal connection 68 of the operating rod with the lever 60 at the inward extreme of the travel of these members. It should also be noted that the pivots 84 and 86 are so located and the arms of the levers 60 and 62 are so chosen that the connecting link 64 is shiftable from one side to the other of the fulcrumed end 84 as indicated in dotted lines in Figure 1. By means of this shifting position of link 64, a snap action is imparted to the mechanism as the pivot pin 66 and the link 64 pass in a straight line through the fulcrum 84. This snap action is effected by tension of the springs 40 and 92 as applied to the above mentioned linkage.

The operation of the device is as follows. With the parts in the full line position shown in Figure 1, which is the normal release position of the mechanism, the spring 92 is relieved of the op erating tension of the mechanism, whereby the spring 40 is free to bias the lever 24 about the fulcrum 32 and thereby open the thumb Hi. However, when the operating knob 12 is is depressed inwardly of the casing 46, the system of links is rotated about the respective fulcrums into the dotted line position shown, and as the link 64 passes its dead-center position about the fulcrum head 84, a snap actuation thereof results. This movement of the linkage results in rotating the lever 16 in a counter-clockwise direction about the pivot 88, thereby extending or tensioning the spring 92 for the dual function of effecting a snap actuation of the linkage about the fulcrum point 84, but primarily to over-ride the opening tension of spring 40, to thereby close the thumb 18 against the action of spring 40. This overriding action is effected by reason of the greatly amplified movement imparted to the pivot or connection point 90 of the spring 92, whereby a greater arcuate movement of the pivot 90 results than of the arcuate movement of the eye 26.

It will be readily apparent from the foregoing description taken in connection with the annexed drawings, that numerous changes and modifications may be resorted to in the accordance with the principles of this invention. Accordingly, it is not desired to limit the invention to the'exact construction shown and described, but all suitable modifications and improvements may beresorted to falling within the scope of the appended claims.

What is claimed as new is as follows: 1. An artificial limb including a hand, a thumb, thumb to said; hand, a

casing simulating a part of a forearm and detachably engaging said hand, a thumb operating snap-action mechanism in said casing, a first spring biasing said thumb to open position and a second spring connecting said thumb with said snap-action mechanism for selectively over-riding said first spring.

2. An artificial limb including a hand, a thumb, a, pivot connecting said thumb to said hand, a casing simulating a part of a forearm and detachably engaging said hand, a thumb operating snap-action mechanism in said casing, a first spring biasing said thumb to open position and a second spring connecting said thumb with said snap-action mechanism for selectively over-riding said first spring, said snap-action mechanism including a plurality of levers, links connecting said levers, said levers being fulcrumed to provide an amplified mechanical movement for operating said thumb.

3. An artificial limb including a hand, a thumb, a pivot connecting said thumb to said hand, a casing simulating a part of a forearm and detachably engaging said hand, a thumb operating snap-action mechanism in said casing, a first spring biasing said thumb to open position and a second spring connecting said thumb with said snap-action mechanism for selectively over-riding said first spring, said snap-action mechanism including a plurality of levers, links connecting said levers, said levers being fulcrumed to provide an amplified mechanical movement for operating said thumb, and means exterior of said casing for operating said snap-action mechanism.

4. An artificial limb including a hand, a thumb, a pivot connecting said thumb to said hand, a casing simulating a part of a forearm and detachably engaging said hand, a thumb operating snapaction mechanism in said casing, a first spring biasing said thumb to open position and a second spring connecting said thumb with said snapaction mechanism for selectively over-riding said first spring, said snap-action mechanism including a plurality of levers, links connecting said levers, said levers being fulcrumed to provide an amplified mechanical movement for operating said thumb, and a frame supporting said snapaction mechanism, said frame being mounted inside said casing.

5. An artificial limb including a hand, a thumb, a pivot connecting said thumb to said hand, a casing simulating a part of a forearm and detachably engaging said hand, a thumb operating snap-action mechanism in said casing, a first spring biasing said thumb to open position and a second spring connecting said thumb with said snap-action mechanism for selectively over-riding said first spring, said thumb being pivoted in said hand by a spherical joint, a fulcrum for said thumb extending transversely through said joint, a lever detachably connected to said thumb and extending rearwardly therefrom, said lever being non-rotatably retained in said thumb by said fulcrum.

6. An artificial limb including a hand, a thumb, a pivot connecting said thumb to said hand, a casing simulating a part of a forearm and detachably engaging said hand, a thumb operating snap-action mechanism in said casing, a first spring biasing said thumb to open position and a second spring connecting said thumb with said snap-action mechanism for selectively over-riding said first spring, said thumb being pivoted in said hand by a spherical joint, a fulcrum for said thumb extending transversely through said joint,

a lever detachably connected to said thumb and extending rearwardly therefrom, said lever being non-rotatably retained in said thumb by said fulcrum, andresilient opening means in said hand engaging said lever.

7. An artificial limb including a, hand, a thumb, a pivot connecting said thumb to said hand, a casing simulating a part of a forearm and detach ably engaging said hand, a thumb operating snapaction mechanism in said casing, a first spring biasing said thumb to open position and a second spring connecting said thumb with said snapaction mechanism for selectively over-riding said first spring, said thumb being pivoted in said hand by a spherical joint, a fulcrum for said thumb extending transversely through said joint, a lever detachably connected to said thumb and extending rearwardly therefrom, said lever being nonrotatably retained in said thumb by said fulcrum, and resilient opening means in said hand engaging said lever, a second spring means engaging said lever and operating means for activating said second spring to over-ride said first spring and close said thumb.

8. The combination of claim 4 wherein said frame comprises a plate, a pair of levers pivoted to said plate intermediate their ends, a connecting link attached .to opposite extremities of said levers, an operating means connected to one of said levers and connecting means engaging the other of said levers and actuating said thumb.

9. The combination of claim 4 wherein said frame comprises a plate, a pair of levers pivoted to said plate intermediate their ends, a connecting link attached to opposite extremities of said levers, an operating means connected to one of said levers and connecting means engaging the other of said levers and actuating said thumb, and an offset channel in said frame providing clearance for said connection of said operating means during its operating travel.

10. The combination of claim 4 wherein said frame comprises a plate, a pair of levers pivoted to said plate intermediate their ends, a, connecting link attached to opposite extremities of said levers, an operating means connecting to one, of said levers and connecting means engaging the other of said levers and actuating said thumb, said connecting means including a third lever pivoted to said frame, said connecting means including a spring attached to said thumb and to said third lever, said second link connecting said third lever with said one of said levers, said levers hav ing their pivots arranged to give an amplified mechanical movement to said last-mentioned spring.

11. The combination of claim 4 wherein said frame comprises a plate, a pair of levers pivoted to said plate intermediate their ends, a connecting link attached to opposite extremities of said levers, an operating means connected to one of said levers and connecting means engaging the other of said levers and actuating said thumb, said pair of levers having their pivots positioned for crossing by said connecting link to provide a snap action.

FRANCIS P. SIMPSON.

REFERENCES CITED FOREIGN PATENTS Country Date Germany May 9, 1916 Number 

